P38A Brakes!

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Grrrrrr

Grrrrrr

Technician, Bodgit & Scarper Ltd
Full Member
Posts
19,297
Location
Buckinghamshire, UK. ('95 DT)
Hi all,

Collective thinking required, please.

Yesterday I jumped in the P38A to nip to the shops. The 3 amigos took a little longer to go out than usual and then I set off. I touhed the brake and the pedal went all the way to the floor! Furiously pumping the car came to a standstill. I then reversed back up the drive. No lights were on but the pedal just had very little resistance and way too much movement. The fluid level seemed low so I topped it up and then parked up and took the bike as I was in a hurry.

I took today off and this morning I checked all lines and brakes - no leaks visible. That's a relief as I replaced the brake-lines and calipers 2 years ago. The pedal was still very soft though. I bled the brake booster unit but I couldn't really see what was happening as I was on my own using one of those non-return valve one-man bleeding things. Nothing seemed out of the ordinary. Anyway, I started the car up and the pedal firmed up, the lights went out as usual and the brakes work! I took it out down the road and back and I don't think the pedal is as hard as it should be but it definitely works. All very strange.

So what could it be?

My current thinking: the accumulator was changed when I got the car 10 years or so ago. Could the nitrogen sphere have failed? That was the fluid would fill the sphere and then when I topped up and ran the car again it has repressurised but obviiously there isn't much gas so pressure cannot be held long. What beats me are there are no lights or faults. The pump doesn't seem to be running more than you'd expect it is just a softer pedal than usual. I live at the top of a hill so I'm a little loathe to risk driving anywhere. Unfortunately the Jag is still SORN'ed waiting for its MoT test so I am without wheels unless I can get the Rangie working. I've ordered brake fluid and will do a full bleed over Christmas. I looked at the pump and accumulator on the scrapper but they look older and more dodgy than the ones currently on there.

Anyone ever had this behavious at all?
 
how many times can you operate the pedal between pump activations? 10 years is a fair time for an accumulator, its likely toast.
if the non return valve has failed then pressure will leak out of the system, meaning the lights stay on longer as it repressurises. pedal is soft when there is no pressure
 
Side conversation...so this is another issue that I didn't know I might have...
Brakes work fine on my 1997 4.0SE: plenty of servo action, pull up straight. All warning lights go out promptly.
Haven't driven for a few days, but got in and switched on.
Pump ran for 35 seconds.
Pressed the pedal once. Pump ran for a second or two.
Subsequent presses of the pedal triggered the pump after 2 or 3 presses, each time for a second or two.
Does that sound normal? I mean as normal as a P38 ever gets, that is.
 
A new accumulator should hold enough pressure that the pump only needs to run on every 4th press of the pedal. By the time it's every press, you should have replaced the accumulator already.
It does depend a bit on how hard you press of course
 
P38 Monkey said:
Side conversation...so this is another issue that I didn't know I might have...
Brakes work fine on my 1997 4.0SE: plenty of servo action, pull up straight. All warning lights go out promptly.
Haven't driven for a few days, but got in and switched on.
Pump ran for 35 seconds.
Pressed the pedal once. Pump ran for a second or two.
Subsequent presses of the pedal triggered the pump after 2 or 3 presses, each time for a second or two.
Does that sound normal? I mean as normal as a P38 ever gets, that is.
Click to expand...
S
Grrrrrr said:
Hi all,

Collective thinking required, please.

Yesterday I jumped in the P38A to nip to the shops. The 3 amigos took a little longer to go out than usual and then I set off. I touhed the brake and the pedal went all the way to the floor! Furiously pumping the car came to a standstill. I then reversed back up the drive. No lights were on but the pedal just had very little resistance and way too much movement. The fluid level seemed low so I topped it up and then parked up and took the bike as I was in a hurry.

I took today off and this morning I checked all lines and brakes - no leaks visible. That's a relief as I replaced the brake-lines and calipers 2 years ago. The pedal was still very soft though. I bled the brake booster unit but I couldn't really see what was happening as I was on my own using one of those non-return valve one-man bleeding things. Nothing seemed out of the ordinary. Anyway, I started the car up and the pedal firmed up, the lights went out as usual and the brakes work! I took it out down the road and back and I don't think the pedal is as hard as it should be but it definitely works. All very strange.
Loss of fluid equals a leak somewhere. That somewhere could well be the sphere. There were no lights on mine when a brake line failed, just a low fluid level warning.

So what could it be?

My current thinking: the accumulator was changed when I got the car 10 years or so ago. Could the nitrogen sphere have failed? That was the fluid would fill the sphere and then when I topped up and ran the car again it has repressurised but obviiously there isn't much gas so pressure cannot be held long. What beats me are there are no lights or faults. The pump doesn't seem to be running more than you'd expect it is just a softer pedal than usual. I live at the top of a hill so I'm a little loathe to risk driving anywhere. Unfortunately the Jag is still SORN'ed waiting for its MoT test so I am without wheels unless I can get the Rangie working. I've ordered brake fluid and will do a full bleed over Christmas. I looked at the pump and accumulator on the scrapper but they look older and more dodgy than the ones currently on there.

Anyone ever had this behavious at all?
Click to expand...

Sounds pretty normal to me.
 
Grrrrrr said:
Hi all,

Collective thinking required, please.

Yesterday I jumped in the P38A to nip to the shops. The 3 amigos took a little longer to go out than usual and then I set off. I touhed the brake and the pedal went all the way to the floor! Furiously pumping the car came to a standstill. I then reversed back up the drive. No lights were on but the pedal just had very little resistance and way too much movement. The fluid level seemed low so I topped it up and then parked up and took the bike as I was in a hurry.

I took today off and this morning I checked all lines and brakes - no leaks visible. That's a relief as I replaced the brake-lines and calipers 2 years ago. The pedal was still very soft though. I bled the brake booster unit but I couldn't really see what was happening as I was on my own using one of those non-return valve one-man bleeding things. Nothing seemed out of the ordinary. Anyway, I started the car up and the pedal firmed up, the lights went out as usual and the brakes work! I took it out down the road and back and I don't think the pedal is as hard as it should be but it definitely works. All very strange.

So what could it be?

My current thinking: the accumulator was changed when I got the car 10 years or so ago. Could the nitrogen sphere have failed? That was the fluid would fill the sphere and then when I topped up and ran the car again it has repressurised but obviiously there isn't much gas so pressure cannot be held long. What beats me are there are no lights or faults. The pump doesn't seem to be running more than you'd expect it is just a softer pedal than usual. I live at the top of a hill so I'm a little loathe to risk driving anywhere. Unfortunately the Jag is still SORN'ed waiting for its MoT test so I am without wheels unless I can get the Rangie working. I've ordered brake fluid and will do a full bleed over Christmas. I looked at the pump and accumulator on the scrapper but they look older and more dodgy than the ones currently on there.

Anyone ever had this behavious at all?
Click to expand...
Low fluid equals a leak somewhere. That somewhere could possibly be the accumulator if after topping up the fluid doesn't drop again..
There were no warning lights on mine when a brake pipe failed other than a low fluid warning.
 
Mark Piercy said:
We had this coming off a slip road at 70mph... No pedal... That was a close call.. The sphere was shot... Once changed over it was all back to "hell breaks loose" when braked hard:D
Click to expand...
I reckon the p38 brakes are very good. Compared with the L322 you have to press harder to get the same response
 
kermit_rr said:
how many times can you operate the pedal between pump activations? 10 years is a fair time for an accumulator, its likely toast.
if the non return valve has failed then pressure will leak out of the system, meaning the lights stay on longer as it repressurises. pedal is soft when there is no pressure
Click to expand...

That's my thinking. The pump is running with just about every press of the pedal too.
 
Datatek said:
Low fluid equals a leak somewhere. That somewhere could possibly be the accumulator if after topping up the fluid doesn't drop again..
There were no warning lights on mine when a brake pipe failed other than a low fluid warning.
Click to expand...

That's what I am thinking. No sign of fluid loss anywhere I can see. Drove it a very ginger 20 miles and didn't seem to get worse.
 
if the pump is running with every press of the pedal and you have no leaks then the accumulator sphere is dead.

When mine died if I pumped the brake pedal I could get the pump to run continuously. ;)

And mine had no brakes for a good few seconds until the pump could get enough pressure in the system.
 
Mark Piercy said:
Less of a tank and more of a car me thinks. ;)
Click to expand...
I got a P38 (my first Range Rover) to avoid the huge tax cost for post-2001 cars (at the time).
I was not then sure about getting a P38 rather than a later L322 which (L322) surely must be a better, improved, fault-free car? Yes?
As I understand it, the P38 is the last of the medieval separate-chassis designs.
The chassis is made out of recycled dreadnought battle cruisers.
The body control system (BeCM) is a 1990's computer, sitting under the driver's seat like Jabba the Hutt.
It was programmed by Darth Vader on a bad day.
The IT outstations were programmed by Eddie Izzard on a good day.
The relationship between an outstation and the BeCM is a bit like that between the SNP and "Westminster".
The engine management system (GEMS) was programmed by a Saudi sheik worried about future oil sales.
I wouldn't know about EAS problems as I have not got one. Nor leaky sun-roof issues.
Then I read some of the truly cosmic L322 problems on here and am thankful for the "elegant simplicity" of my P38...
 
Mark Piercy said:
We had this coming off a slip road at 70mph... No pedal... That was a close call.. The sphere was shot... Once changed over it was all back to "hell breaks loose" when braked hard:D
Click to expand...
Scary - not exactly a fail-safe system. I think my accumulator is OK - is that what you mean by "sphere"? Does mine in the photo look OK do you think?
Thank you...!

brake accumulator.jpg
 
P38 Monkey said:
I got a P38 (my first Range Rover) to avoid the huge tax cost for post-2001 cars (at the time).
I was not then sure about getting a P38 rather than a later L322 which (L322) surely must be a better, improved, fault-free car? Yes?
As I understand it, the P38 is the last of the medieval separate-chassis designs.
The chassis is made out of recycled dreadnought battle cruisers.
The body control system (BeCM) is a 1990's computer, sitting under the driver's seat like Jabba the Hutt.
It was programmed by Darth Vader on a bad day.
The IT outstations were programmed by Eddie Izzard on a good day.
The relationship between an outstation and the BeCM is a bit like that between the SNP and "Westminster".
The engine management system (GEMS) was programmed by a Saudi sheik worried about future oil sales.
I wouldn't know about EAS problems as I have not got one. Nor leaky sun-roof issues.
Then I read some of the truly cosmic L322 problems on here and am thankful for the "elegant simplicity" of my P38...
Click to expand...
Here here:D
 
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